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Fat supplementation has potential to improve reproductive performance and increase pregnancy rates in cattle by increasing the energy density of the diet. However, some of the positive effects of fat seem to be influenced by the type of fatty acid fed. Docosahexaenoic acid (DHA , 22:6n-3) and eicosapentaenoic acid (EPA , 20:5n-3) are long-chain n-3 poly-unsaturated fatty acids (PUFA) that have important biological effects on reproduction through their involvement in hormone and series 3 prostaglandin synthesis. Ruminant tissues are naturally almost devoid of n-3 long-chain PUFA, specifically EPA and DHA. Algae biomass provides a consistent source of DHA and EPA that could be fed to alter hormonal profiles and improve reproduction of beef heifers. Eighty-eight Angus × Simmental heifers (427 ± 1.8 kg body weight [ BW ]) were blocked by BW and allotted to 2 treatments (44/treatment, 4 pens/treatment, 11 heifers/pen). Control heifers were fed a diet that contained (dry matter [ DM ] basis) 52.8% mixed grass silage, 32% corn silage, and 15.2% concentrate. DHAgold (49% fat; 21.8% DHA; DSM Inc.) was included in the algae diet at 1.65% DM, replacing equal parts of corn and DDGS. Diets were formulated to contain 12% crude protein and 0.85 Mcal/kg net energy for gain (NEg). Heifers were fed treatment diets from 54 d prior to the breeding season through the first trimester. Follicular fluid was collected on day 47 for hormonal analysis. Artificial insemination (AI) was from days 54 to 77. Heifers that did not get pregnant to AI were removed from the study on day 109 and placed with a bull. The study ended on day 180. Data were analyzed using the MIXED procedure of SAS. During the pre-breeding period, algae heifers had lesser dry matter intake (P  = 0.006) compared to control heifers. Heifers supplemented with algae had a greater average daily gain (P  = 0.03) during the breeding period and BW tended (P  = 0.06) to be greater for algae compared to control heifers on day 98 and was greater on day 180 (P  = 0.03). Dominant follicle diameter and follicular estrogen concentration were unaffected by treatment (P  ≥ 0.12). Follicular insulin-like growth factor-1 was greater in algae compared to control heifers (P  = 0.03). First service conception rate did not differ between treatments (P  = 0.67); however, second service and overall conception were lesser (P  ≤ 0.03) in algae compared to control heifers. These data suggest supplementing DHA-rich algae improved growth but decreased conception rates of primiparous beef females. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of a dry versus a molasses-based liquid supplement on ruminal butyrate concentration, gastrointestinal tract (GIT) barrier function, inflammatory status, and performance of newly received feedlot cattle. In experiment 1, 60 mixed breed steers (234 ± 2.1 kg) were weaned, held overnight at a sale barn, then transported 14 h to Purdue University. After arrival, steers were weighed, blocked by body weight, and allotted within block to treatments (six pens per treatment and five steers per pen). Diets consisted of 45% roughage and 55% concentrate (dry matter basis). Treatments differed in the supplement source as follows: DRY: 10% dry supplement or LIQUID : 10% liquid molasses-based supplement. Feed intake, average daily gain (ADG), and gain:feed were determined for the three 21-d periods and overall. In experiment 2, 16 crossbred heifers (246 ± 7.5 kg) were used (8 heifers per treatment). Diets were the same as in experiment 1 and were fed for 60 d. On d 56 ruminal fluid samples were collected at 0, 3, 6, and 9 h after feeding. To mimic a stress event, heifers were transported for 4 h on d 61, rested overnight, and transported 12 h on d 62. Blood was collected from heifers immediately prior to transport and immediately upon their return. Gut barrier function using a Cr-EDTA marker was determined after transportation. Data were analyzed using the GLIMMIX procedure of SAS. Steers fed the liquid supplement had greater (P  ≤ 0.03) ADG through d 42 and overall compared to steers fed the dry supplement. Feed intake did not differ (P  = 0.25) between treatments from d 0 to d 21. However, steers fed the liquid supplement showed greater (P  < 0.001) dry matter intake after d 21 and overall compared to those fed the dry supplement. Steers fed the liquid supplement tended (P  < 0.09) to have reduced serum haptoglobin and lipopolysaccharide-binding protein (LBP) compared to those fed the dry supplement. Heifers fed the liquid supplement had greater (P  = 0.02) Cr in urine and tended (P  = 0.07) to have lower serum LBP after transport compared to those fed the dry supplement. Heifers fed the liquid supplement had 72% lower serum haptoglobin before, but only a 19% lower serum haptoglobin after transport compared to animals fed the dry supplement (treatment × time; P  = 0.07). Therefore, the liquid supplement altered GIT barrier function, and improved inflammatory status, resulting in increased growth of receiving cattle. [ABSTRACT FROM AUTHOR]

Oral administration of indigestible markers and subsequent urine collection is a useful method to determine in vivo gastrointestinal tract (GIT) permeability in cattle for research purposes. However, urine sampling techniques often rely on total waste collection, which reduces the ability to perform more frequent sampling and obtain accurate volumes and sterile samples. An alternative is urethral catheterization, though the feasibility of this technique has not been thoroughly tested in preweaned Holstein heifer calves. The study objective was to develop a urethral catheter placement procedure in preweaned Holstein heifer calves for continuous and accurate urine collection to evaluate GIT permeability using an indigestible marker. Fifteen Holstein heifer calves had catheters placed at approximately 1 wk (8.0 ± 1.5 d) and 6 wk (40.0 ± 1.5 d) of age. During the procedure, calves were individually housed and restrained. The vulva was sterilized and then a sterile, lubricated speculum was inserted into the vagina. A sterile 0.09 cm diameter guidewire was guided into a lubricated, sterile 10 French Foley catheter. The catheter was inserted at approximately 5 through 7 cm into the urethral opening, guided into the bladder, and the catheter balloon was filled with 10 mL of water. The guidewire was removed, and urine flow confirmed correct placement before a 4-L urinary drainage bag was attached to the catheter. After catheterization (24 h), 1 L of chromium (Cr)-ethylenediaminetetraacetic acid was orally dosed to the calves. Calf health observations were made six times over a 48-h period, and any occurrence of vaginal discharge, tissue discharge in catheter, bleeding, inflammation, or abnormal urine was considered a localized reaction. The proportion of localized reactions for each age group was determined using Microsoft Excel, and the total Cr output was analyzed using PROC GLIMMIX. Localized reactions occurred for 20.0% of the 1-wk-old calves and 13.3% of the 6-wk-old calves. In the first 4 h, urine was collected every 15 min, and there were no overall Cr output differences (P = 0.38; 10.28 ± 3.21 mg Cr) when comparing 1- and 6-wk-old calves. However, 1-wk-old calves tended (P = 0.08) to have greater overall Cr output at 480 min (19.2%) and 1,440 min (41.9%) when compared with 6-wk-old calves. In summary, urinary catheterization is a viable urinary collection method for the determination of in vivo GIT permeability in preweaned Holstein heifer calves. [ABSTRACT FROM AUTHOR]

One hundred and forty-four Angus × Simmental steers were allotted by body weight (BW ; 363 kg), breed composition, and farm origin to a 3 × 2 factorial arrangement of six treatments (4 pens per treatment) to determine the effect of Mootral (garlic + citrus extract; 0.25% of the diet dry matter [ DM ] vs. 0.0%) on methane (CH 4 ) emissions, growth, and carcass characteristics of feedlot cattle. During the first 84 d, cattle were fed three different forage concentrations in the diet (15%, 41.5%, or 68% corn silage) with or without Mootral. From day 85 to slaughter, corn silage was included at 15% of the diet DM with or without Mootral. CH4 emissions were measured on day 42 to 46 and day 203 to 207. Data were analyzed using the GLIMMIX procedure of SAS. Mootral did not affect CH4 emissions on days 42 to 46 (P ≥ 0.47), but there was a forage effect, where steers fed the 68% corn silage emitted more CH4 on a g/d (P = 0.05) and a g/kg of dry matter intake (DMI ; P = 0.007) basis and tended (P = 0.07) to produce more CH4 on g/kg BW basis compared to steers fed the 15% corn silage diet. On day 203 to 207, steers fed Mootral emitted less (P ≤ 0.03) CH4 on a g/d, g/kg DMI, and g/kg BW basis compared to steers not fed Mootral. There was an interaction (P = 0.03) between forage concentration and Mootral for DMI from day 0 to 84, where Mootral decreased DMI of steers fed 15% corn silage but did not affect DMI of steers fed 41.5% or 68% corn silage. There were no effects (P ≥ 0.22) of forage concentration or Mootral on BW or average daily gain at any time, or on DMI from day 84 to slaughter and overall. However, overall calculated net energy for maintenance (NE m ) and net energy for gain (NE g ) tended to be greater for steers fed Mootral (P ≤ 0.10). Intake from day 0 to 84 was lower and gain:feed from day 0 to 84 and overall was greater (P = 0.04) for steers fed 68% compared to steers fed 41.5% corn silage. Calculated NEm and NEg from day 0 to 84 and overall were greater for steers fed 68% corn silage compared to steers fed 41.5% corn silage (P ≤ 0.03). Mootral tended to decrease (P ≤ 0.09) fat thickness and yield grade. In conclusion, increasing forage concentration increased CH4 emissions and Mootral decreased CH4 production in 15% corn silage diets and tended to improve carcass leanness. [ABSTRACT FROM AUTHOR]

The addition of an exogenous glucoamylase enzyme preparation to feedlot diets that contain a high percentage of corn silage may improve digestibility and yield positive outcomes in growth and efficiency. However, it is unclear what concentration of corn silage in the diet would most benefit from exogenous glucoamylase. Crossbred steers [n = 180; body weight (BW) = 459 ± 11.8 kg] were divided into 30 pens (5 pens per treatment; 6 steers per pen) and assigned to one of six treatments arranged as a 3 x 2 factorial investigating 3 forage concentrations (15, 42, and 69% corn silage) and 2 exogenous glucoamylase additions (0 or 183 enzyme units/kg of dry matter per d). Steers were fed 42% corn silage, 30% corn, 23% dried distillers grains with solubles, and 5% supplement at feedlot entry and for 2 wk prior to initiation of the study. Steers on the 15% and 69% corn silage diets were transitioned to treatment diets by wk 3 of the study (d 15), with the first transition occurring on d 0. Diet transitions occurred once weekly. The animals were on feed for 105 ± 10.4 d and had ad libitum access to feed and water. Average daily gain (ADG), dry matter intake (DMI), and gain:feed were assessed both overall and for two distinct periods: d 0 to 50, and d 51 until slaughter. Data analysis was performed using the GLIMMIX procedure of SAS. From d 0 to 50, ADG, DMI, and gain:feed did not differ due to forage concentration or enzyme inclusion and there was no interaction (P ≥ 0.39). For d 51 to slaughter, enzyme inclusion interacted with forage concentration such that the enzyme improved ADG (P = 0.0003) and gain:feed (P = 0.01) for steers fed the 42% corn silage diet but did not effect ADG and gain:feed for steers fed the 15 or 69% corn silage diets. For d 51 to slaughter DMI was not affected by forage concentration, enzyme inclusion, or their interaction (P ≥ 0.21). When calculated for the entire study (d 0 to slaughter), increasing forage concentration decreased ADG and gain:feed (P ≤ 0.0006), but did not effect DMI (P = 0.22). Overall, enzyme addition did not impact ADG, DMI, or gain:feed and did not interact with forage concentration (P ≥ 0.50). Carcass characteristics were not affected by forage concentration, enzyme addition, or their interaction (P ≥ 0.19). Overall results suggest that an exogenous glucoamylase enzyme improves growth and efficiency of heavier feedlot cattle fed moderate amounts of forage later in the feeding period. [ABSTRACT FROM AUTHOR]

Stress negatively affects the gastrointestinal tract (GIT) barrier function, resulting in compromised animal health. A deeper understanding of how diet and stress impacts the GIT barrier function in feedlot cattle is needed. Aspirin decreases mucus production and mucosal repair in the GIT and could be used as a model for GIT barrier dysfunction research. The objective of this study was to evaluate the effectiveness of aspirin to induce GIT barrier dysfunction in beef cattle. In experiment 1, sixteen crossbred heifers (425.0 ± 8.6 kg) were allotted to 0, 50, 100, or 200 mg/kg body weight (BW) aspirin doses based on BW. Experiment 1 consisted of two periods separated by 4 wk where four heifers per treatment received the same aspirin dose during each period. Heifers were fed a 49.4% corn silage and 50.6% concentrate diet. The 200 mg/kg BW aspirin treatment was dosed as a 100 mg/kg BW aspirin oral bolus 36 and 24 h prior to Cr-ethylenediaminetetraacetic acid (EDTA) dosing (1 liter; 180 mM). The 50 and 100 mg/kg BW aspirin treatments were dosed as an oral bolus 24 h prior to Cr-EDTA dosing. Urine was collected every 3 h for 48 h and analyzed for Cr. Serum was collected at 0 and 48 h and analyzed for lipopolysaccharide-binding protein (LBP), interleukin-6, serum amyloid A (SAA), haptoglobin, and aspartate aminotransferase. In experiment 2, sixteen crossbred steers (576.0 ± 14.2 kg) fed a similar diet were allotted by BW to the 0 and 200 mg/kg BW aspirin treatments (eight steers/treatment) and were slaughtered 24 h after the last dose. Jejunal tissues were collected, and claudin (CLDN) 1, 2, and 3, occludin, and zonula occludens tight junction messenger ribonucleic acid (mRNA) expression was determined. Data were analyzed using the MIXED procedure of SAS. Urinary Cr excretion increased linearly at hours 3, 6, 9, and 12 (P ≤ 0.04) as aspirin dose increased from 0 to 200 mg/kg. Aspirin linearly increased Cr absorption (P = 0.02) and elimination (P = 0.04) rates and linearly decreased mean retention time of Cr (P = 0.02). Aspirin increased SAA (P = 0.04) and tended to increase LBP (P = 0.09) in serum but did not affect any other serum inflammatory marker (P ≥ 0.19). Aspirin tended to increase jejunal CLDN-1 mRNA expression (P = 0.10) but did not affect the mRNA expression of other genes regulating tight junction function (P ≥ 0.20). Results from this study indicate that aspirin disrupts the GIT barrier function in beef cattle and has a potential as a model in GIT permeability research. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of soybean hulls (SBH) and/or calcium oxide (CaO) on rumen pH, digestibility, and performance of steers fed diets containing dried distillers grains with solubles (DDGS). In experiment 1, Angus × Simmental steers (n = 112, body weight [BW] = 364 ± 7.8 kg) were allotted to 1 of 4 diets arranged as a 2 × 2 factorial and placed in 16 pens (7 steers/pen, 4 pens/treatment, and 28 steers/treatment). Factors were SBH (0% or 30% of diet dry matter [DM]) and CaO (0% or 1%) inclusion. Basal diets contained 20% corn stover, 30% DDGS, and 4% supplement. Diets with SBH contained 14.1% or 15.0% corn and diets without SBH contained 43.9% or 44.8% corn. In experiment two, four steers (BW = 510 ± 9.8 kg) were allotted to a 4 × 4 Latin square (21 d periods) to determine the effects of CaO and SBH on ruminal pH, volatile fatty acid (VFA), nutrient digestibility, and digestion kinetics. Statistical analyses were conducted using the MIXED procedure of SAS. In experiment 1, BW did not differ among treatments (P ≥ 0.46). Overall carcass-adjusted gain did not differ due to SBH or CaO inclusion (P ≥ 0.13); however, there was an interaction (P = 0.01) where CaO improved gain in steers fed no SBH, but not in steers fed SBH. Steers fed SBH consumed more DM than steers not fed SBH (P = 0.02) and an interaction tended to occur (P = 0.06) where CaO increased dry matter intake in steers fed no SBH, but not in steers fed SBH. Calcium oxide increased hot carcass weight and yield grade (interaction; P ≤ 0.04) and tended to increase fat thickness (interaction; P = 0.08) in steers fed no SBH, but not in steers fed SBH. Dressing percentage, longissimus muscle area, % kidney, pelvic, heart fat, and marbling score did not differ among treatments (P ≥ 0.14). Total VFA concentrations were greater with SBH inclusion and with CaO addition (P < 0.01). Digestibility of DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) was greater with CaO addition (P ≤ 0.04) and NDF and ADF digestibility were greater with SBH inclusion (P < 0.001). Inclusion of SBH did not affect (P ≥ 0.26) rate of digestion (k d) or passage (k p). Addition of CaO tended to increase mean retention time (P = 0.09). An interaction between SBH inclusion and CaO addition occurred for k d (P = 0.01), where CaO increased k d in steers fed SBH, but decreased k d when steers were fed no SBH. Total N excretion tended to be lower with SBH inclusion and CaO addition (P = 0.07). In conclusion, CaO enhances performance of cattle fed corn, DDGS, and corn stover diets, but not when corn is partially replaced by a fiber-based energy feed. [ABSTRACT FROM AUTHOR]

One hundred twenty Angus × Simmental steers [322 ± 4.8 kg initial body weight (BW)] were blocked by BW and randomly allocated to 4 treatments arranged as a 2 × 2 factorial to evaluate the effects of supplemental arginine (none or 63 g/d of a 15.6% metabolizable arginine), supplemental lysine (none or 40 g/d of a 25% metabolizable lysine), and their interaction on performance and carcass composition of feedlot steers during a 170-d feeding period. The basal diet [dry matter (DM) basis] contained 52% dry-rolled corn, 22% dried distillers grains with solubles, 20% corn silage, and 6% vitamin-mineral supplement. Lysine balance was estimated to be −10.3 to −10.8 g for diets that did not contain supplemental lysine, and arginine supply was estimated to be +9.7 g for diets that did not contain supplemental arginine during period 1 (days 0 to 87). Lysine and arginine supplies met or exceeded requirements in period 2 (days 88 to 170). Rumen-protected arginine and lysine were top dressed daily until slaughter at a common BW (622 ± 5.5 kg). Data were analyzed using the MIXED procedure of SAS. Body weight, average daily gain, and DM intake were not affected (P ≥ 0.14) by arginine or lysine supplementation. However, lysine increased gain:feed (P = 0.05) during period 1. Lysine decreased serum urea nitrogen (P = 0.03) on day 87, increased (P = 0.01) longissimus muscle (LM) area, decreased (P ≤ 0.01) fat thickness and yield grade, and tended (P = 0.06) to increase moisture content of LM steaks. There tended to be an interaction for moisture content of steaks (P = 0.09), where arginine supplementation increased moisture content to a greater extent in steaks from cattle supplemented with lysine compared with steaks from cattle not fed supplemental lysine. Arginine tended to increase the proportion of Choice grade carcasses (P = 0.09) but did not change lipid content of steaks (P = 0.59). Arginine tended to decrease serum glutamate (P = 0.09) and lysine (P = 0.07) after 87 d of feeding. In conclusion, supplemental rumen-protected arginine and lysine did not improve performance, but lysine can increase carcass muscle and leanness, and although arginine did not increase lipid content of steaks, it may favorably shift carcasses to a greater quality grade. [ABSTRACT FROM AUTHOR]

Three experiments were conducted to determine the effectiveness of calcium hydroxide (Ca(OH)2) addition and roughage inclusion on digestibility, performance, and carcass characteristics of steers fed 60% dried distillers grains with solubles (DGS). Statistical analyses for studies were conducted using the MIXED procedures of SAS. In experiment 1, 48 steers (353.5 ± 7.55 kg) were allotted to individual pens and fed 1 of 3 diets (dry matter [DM] basis) containing 60% dried DGS, 20% corn silage, and 4% supplement with: 1) 14.5% corn and no Ca(OH)2; 2) 14% corn and 2% Ca(OH)2; and 3) 14.5% additional corn silage and no Ca(OH)2. Steers fed Ca(OH)2 consumed the least (P = 0.03) and steers fed added corn silage consumed the most and had the least gain:feed (P = 0.02). Gain and carcass quality were not affected by treatment (P ≥ 0.48). In experiment 2, 112 steers (375.3 ± 19.25 kg) were allotted to pens (four pens per treatment; seven steers per pen) arranged as a 2 × 2 factorial (roughage × Ca(OH)2) and fed one of four diets (DM basis) containing 60% dried DGS, 17% corn silage, and 4% supplement with: 1) 17.5% corn silage and no Ca(OH)2; 2) 17% corn silage and 2% Ca(OH)2; 3) 17.25% corn stover and no Ca(OH)2; and 4) 17% corn stover and 2% Ca(OH)2. Added stover decreased average daily gain (ADG) compared to added corn silage (P = 0.04). Ca(OH)2 increased ADG when steers were fed stover, but not when steers were fed only corn silage (P = 0.05; interaction). In experiment 3, six ruminally cannulated steers (initial body weight = 352 ± 14.8 kg) were randomly allotted to a 6 × 6 Latin square design to determine the effects of roughage inclusion (corn, corn silage, stover) and Ca(OH)2 addition (0% or 2%) on ruminal characteristics. Feeding stover decreased total volatile fatty acid(s) (VFA) concentration and DM digestibility compared to corn silage or corn (P < 0.01), whereas Ca(OH)2 resulted in greater total VFA concentrations and DM digestibility (P ≤ 0.02). Stover increased rate of DM degradation (K d) and rate of particle outflow from the rumen (P ≤ 0.04) but decreased extent of DM digestion and mean retention time (P ≤ 0.02) compared to corn or silage. Ca(OH)2 increased K d (P < 0.01) and tended to increase (P = 0.06) liquid passage rate. In conclusion, added roughage did not improve performance of cattle fed 60% dried DGS. Ca(OH)2 may decrease intake and maintain performance of cattle fed 60% dried DGS with corn silage as the roughage source and increases ADG when corn stover replaces a portion of the corn silage. [ABSTRACT FROM AUTHOR]

A 2-part experiment was conducted to determine the effects of a blend of specialized mannan- and glucan-rich fractions of yeast (Select-TC, Alltech Inc.) on the health status and performance of steers during the first 2 mo of the feedlot period. Eighty crossbred steers were acquired from commercial sale barns in Mississippi and Georgia and transported to Purdue University. All animals were fed a corn silage-based receiving diet and were checked and treated daily for respiratory disease as needed following established treatment protocols. In Exp. 1, 64 steers (246.5 ± 4.7 kg initial weight) were blocked by BW and randomly allocated to 2 treatments to determine the impact of supplementation of a hydrolyzed mannan- and glucan- rich yeast fraction for 56 d on BW, ADG, daily DMI, and G:F: hydrolyzed yeast fed at 13 g (as-fed)/steer daily (TC) or nonsupplemented control (CON). Steers in Exp. 1 were housed in bedded pens with 2 animals per pen [n = 16 pens (32 steers)/treatment]. In Exp. 2, 16 steers (247.1 ± 5.4 kg initial BW) were similarly allotted to 2 treatments (CON and TC), individually penned, and subjected to a lipopolysaccharide (LPS) endotoxin challenge on day 62 or 63 after the start of the study to determine the animal's response to an inflammatory agent. Serum samples and rectal temperatures were taken every half an hour from -2 to 8 h relative to LPS injection from steers in Exp. 2. Data were analyzed as a complete randomized block design using the MIXED procedure of SAS. Morbidity for both experiments did not differ (P = 0.16). Weight, ADG, DMI, and G:F did not differ among treatments (P = 0.32) in Exp. 1. After the LPS infusion in Exp. 2, rectal temperatures (P = 0.03) and serum NEFA concentration (P = 0.04) were decreased in TC compared with CON steers. Concentrations of blood urea nitrogen (P = 0.31), glucose (P = 0.70), insulin (P = 0.57), and cortisol (P = 0.77) did not differ by treatment after LPS administration. Serum IL-6 concentrations were decreased (P < 0.0001), and interferon-γ concentrations tended to be greater (P = 0.07) in TC compared with CON steers after LPS infusion. Serum cytokine and metabolite results indicate that Select-TC improved health and metabolic status of LPS-challenged cattle, but this did not result in quantifiable improvements in performance in the conditions observed in this study. [ABSTRACT FROM AUTHOR]

Heterotrophic production of microalgae biomass provides a consistent, high-quality source of docosahexaenoic acid (DHA; C22:6 n-3) in triglyceride oils that could be used as a ration supplement for feedlot steers to improve nutritional qualities of beef. Sixty Angus × Simmental steers (438 ± 6.4 kg) were allotted to two treatments (30 steers each, six pens, five steers/pen) to determine the effects of ForPLUS (DHA-rich microalgae Aurantiochytrium limacinum; 63.6% fat; 17.9% DHA; 30 mg/kg Sel-Plex; Alltech Inc.) on performance, insulin sensitivity, LM fatty acid composition, and meat quality. Steers were fed basal diets containing 45% corn, 30% distillers dried grains with solubles, 20% corn silage, and 5% supplement. Basal diets were formulated to contain 16.1% CP and 1.32 Mcal/kg NEg. Treatments were delivered to steers in a ground corn-based top-dress (454 g total/steer) and contained no microalgae for control steers or 100 g/steer daily of ForPLUS for microalgae steers. A glucose tolerance test (GTT) was performed 10 d prior to slaughter. Steers were slaughtered when a target pen BW of 621 kg was achieved. Fatty acid oxidation potential was determined by measuring thiobarbituric acid reactive substances (TBARS) on LM samples collected 24 h after slaughter and aged for 48 h or 21 d. Weight and BW gain did not differ during the study (P = 0.13); however, steers fed microalgae remained in the feedlot seven more days compared to steers fed the control diet (111 vs. 104 d; P = 0.04). Overall DMI decreased (P = 0.002) and G:F increased during the second half of the study (P = 0.04) in steers fed microalgae compared to steers fed the control diet. Steers fed microalgae secreted less insulin (P = 0.01) and took longer to clear glucose (P = 0.01) during a 2-h GTT. Carcass traits did not differ between treatments (P = 0.23). Microalgae had no effect on n-6 content (P = 0.67), but more than doubled the n-3 fatty acid percentage and the n-3:n-6 ratio of the LM (P < 0.0001). The percentage of n-3 fatty acids C20:5 and C22:6 were increased (P < 0.0001) 4-fold and 6.25-fold, respectively, by microalgae supplementation. Concentration of TBARS did not differ in LM aged for 48 h (P = 0.91); however, when aged for 21 d, steers fed microalgae tended to produce LM with greater TBARS concentration compared to steers fed the control diet (P = 0.08). In conclusion, DHA-rich microalgae decreased DMI of steers, and increased n-3 fatty acids and beef oxidation in steaks aged for 21 d. [ABSTRACT FROM AUTHOR]

There are a variety of acute and chronic psychological and physical stressors associated with management practices used in beef production systems. Primary challenges in feedlot cattle include heat stress, acute and subacute acidosis, weaning, transportation, feed deprivation/restriction, and social mixing/crowding. These stressors disturb the homeostatic state of the host and microbiome and cause acute or chronic inflammation resulting in damage to the gastrointestinal tract (GIT) epithelial barrier that leaves the animal vulnerable to enteric pathogens and toxins. A breach of the small intestinal barrier (leaky gut) allows unwanted pathogens and toxins to infiltrate into blood, causing infection, depressed feed intake, and diverts nutritional resources away from anabolic processes. We have demonstrated that intentionally inducing GIT inflammation in feedlot cattle with aspirin, which is known to cause mucosal injury and increase GIT barrier dysfunction, provides a model system to better understand the metabolic cost of leaky gut in grainfed feedlot cattle. Indeed, aspirin increased leakage of chromium-EDTA into urine, raised serum concentrations of lipopolysaccharide binding protein (LBP), decreased growth by 4.5 to 8.5%, and re-partitioned carcass components from lean tissue (rib-eye area) into fat. Thus, the chronic inflammatory effects of leaky gut have the potential to create a significant economic loss. Our work also shows that in-feed administration of monensin and tylosin have offered a solution to the non-specific immune response observed in grain-fed cattle by increasing jejunal villus height to crypt depth ratio, diminishing leaky gut, and decreasing serum LBP. Finally, we have observed that molasses based liquid supplements increase ruminal butyrate concentration, resulting in improved gut barrier function, decreased serum inflammatory markers, and greater DMI and ADG in newly received feedlot cattle fed a 30% roughage diet. [ABSTRACT FROM AUTHOR]

Urine collection is a useful tool to analyze intestinal permeability in cattle for research and diagnostic purposes. However, urine sampling techniques often rely on total waste collection, which reduces the ability to perform more frequent sampling and obtain accurate and sterile urine volumes. A potential alternative is urethral catheters, which have been used in cows and weaned heifers. However, urethral catheters have not been thoroughly tested in pre-weaned dairy heifer calves. The study objective was to develop a urethral catheter placement procedure in pre-weaned heifer calves for continuous and accurate urine collection. Fifteen Holstein heifer calves had catheters placed at 8 ± 2 days (37.5 ± 3.38 kg BW) and 40 ± 2 days (59.3 ± 5.38 kg BW) of age. During the procedure, calves were individually housed (1.87 m2/calf) and restrained. The vulva was cleaned using betadine and 70% ethanol and then a sterile, lubricated 8.9 cm speculum was inserted into the vagina. A sterile guidewire (145 cm x 0.89 cm) was inserted into a lubricated sterile 10 FR catheter. The catheter was inserted into the urethral opening (~5-7 cm into vagina), guided into the bladder, and the catheter balloon was filled with water (10 mL). The guide wire was removed, and urine flow confirmed correct placement before a 4 L urinary drainage bag was attached to the catheter. Individual calf health observations were made twice over a 24-hour period and included vaginal discharge, bleeding, redness or inflammation, and tissue discharge in the urine. Occurrence rate was determined using PROC FREQ in SAS 9.4. Regardless of catheterization timing, bleeding and tissue discharge occurred at a rate of 3.33% ± 0.18, and vaginal discharge and inflammation occurred at a rate of 6.70% ± 0.25. In summary, this procedure is a viable method for total urine collection in pre-weaning heifer calves. [ABSTRACT FROM AUTHOR]

Stress negatively effects gastrointestinal tract (GIT) barrier function, resulting in compromised animal health. The objective of this study was to evaluate the effectiveness of aspirin to intentionally induce GIT barrier dysfunction in beef cattle. In experiment 1, sixteen crossbred heifers (425 ± 8.6 kg) were enrolled in 2 experimental periods and allotted by BW to 0, 50, 100, or 200 mg/kg BW aspirin. Four heifers per treatment received the same aspirin dose during each period, which were separated by 4 wks. Heifers were fed a 49.4% corn silage, 50.6% concentrate diet. Aspirin was delivered to animals as an oral bolus. The 200 aspirin treatment was dosed as 100 mg/kg BW aspirin 36 and 24 h prior to Cr-EDTA dosing (1 L; 180 mM). The 50 and 100 aspirin treatments were dosed 24 h prior to Cr-EDTA dosing. Urine was collected every 3 h for 48 h and analyzed for Cr using atomic absorption spectrometry. Serum was collected at 0, 24, and 48 h and analyzed for lipopolysaccharide binding protein (LBP) and interleukin-6 (IL-6) using ELISA. In experiment 2, sixteen crossbred steers (576 ± 14.2 kg) fed the same diet were allotted by BW to the 0 and 200 mg/kg BW aspirin treatments (8 steers/treatment) and were slaughtered 24 h after the last dose. Jejunal tissues were collected and tight junction mRNA expression was determined. Data were analyzed using the MIXED procedure of SAS. Aspirin linearly increased Cr absorption (P = 0.02) and elimination (P = 0.04) rate and linearly decreased mean retention time of Cr (P = 0.02). Aspirin tended to increase jejunal claudin-1 mRNA expression (P = 0.10) but did not affect serum IL-6 or LBP or expression of other jejunal tight junction mRNA (P ≥ 0.20). This study indicates that aspirin disrupts GIT barrier function in beef cattle and has potential as a model in GIT permeability research. [ABSTRACT FROM AUTHOR]

One hundred and forty-four Angus x Simmental steers were allotted by body weight (BW; 363 kg, breed composition, and farm origin to a 3 x 2 factorial arrangement of 6 treatments (4 pens per treatment) to determine the effect of Mootral (garlic + citrus extract; 0.25% of the diet DM vs. 0.0%) on methane emissions, growth and carcass characteristics of feedlot cattle. During the first 84 days, cattle were fed three different diets (forage content of 15, 41.5, or 68% corn silage). From day 85 to slaughter, corn silage was included at only 15% of the diet DM. Data were analyzed using the MIXED procedure of SAS. There was an interaction (P = 0.03) between forage content and Mootral for DMI from d 0 to 84, where Mootral decreased DMI of steers fed 15% corn silage, but did not affect DMI of steers fed 41.5 or 68% corn silage. There were no effects (P ≥ 0.22) of forage content or Mootral on BW or average daily gain at any time, or on DMI from d 84 to slaughter and overall. Gain-feed ratio from d 0 to 84 and overall was greater (P = 0.04) for steers fed 68% compared to 15 or 41.5% corn silage. On d 41, steers fed 41.5 and 68% corn silage had increased (P ≤ 0.02) methane emissions compared to steers fed 15% corn silage. There tended to be an interaction (P ≤ 0.09) between forage content and Mootral for methane emissions (g/d) on d 41 and 203, where steers fed Mootral showed lesser methane emissions with 15% corn silage, but not with the 41.5 and 68% corn silage diets. Steers fed Mootral showed lesser (P ≤ 0.03) methane emissions on d 203. Mootral tended to decrease (P < 0.10) fat thickness and yield grade. In conclusion, Mootral decreased methane production in 15% corn silage diets and improved carcass leanness. [ABSTRACT FROM AUTHOR]

Algae biomass provides a consistent source of docosahexaenoic acid (DHA), an omega-3 fatty acid, that could be used to alter hormonal profiles and improve reproduction of beef heifers. Eighty-eight Angus × Simmental heifers (427 ± 1.8 kg) were blocked by BW and allotted to 2 treatments (44/treatment, 4 pens/treatment, 11 heifers/pen). Control heifers were fed a diet that contained (DM basis) 52.8% mixed grass silage, 32% corn silage, and 15.2% concentrate. DHAgold (49% fat; 21.8% DHA; DSM Inc.) was included in the algae diet DM at 1.65%, replacing equal parts of corn and DDGS. Diets were formulated to contain 12% CP and 0.79 Mcal/kg NEg. Heifers were fed treatment diets from 54 d prior to the breeding season through the first trimester. Follicular fluid was collected on day 47 for hormonal analysis. Artificial insemination (AI) breeding was from d 55 to 98, after which open heifers were removed to 1 control and 1 algae pen and placed with a bull. The study ended on d 180. Performance data were analyzed using the MIXED procedure and conception data were analyzed using the GLIMMIX procedure of SAS. Dominant follicle diameter and follicular estrogen concentration were unaffected by the treatment (P ≥ 0.12). Follicular insulin-like growth factor-1 was greater in algae compared to control heifers (P = 0.03). During the pre-breeding period, algae heifers had lesser DMI (P = 0.006) compared to control heifers. Heifers supplemented with algae had greater ADG (P = 0.03) during the breeding period and BW tended to be greater for algae compared to control heifers on d 98 and 180 (P ≤ 0.07). First service conception rate did not differ between treatments (P = 0.67); however, second service tended (P = 0.08) and overall conception was (P = 0.03) lesser in algae compared to control heifers. These data suggest supplementing DHA-rich algae improved growth but decreased conception rates of beef heifers. [ABSTRACT FROM AUTHOR]

One hundred twenty Angus × Simmental steers [322 ± 4.8 kg initial body weight (BW)] were blocked by BW and randomly allocated to 4 treatments arranged as a 2 × 2 factorial to evaluate the effects of supplemental arginine (none or 63 g/d of a 15.6% metabolizable arginine), supplemental lysine (none or 40 g/d of a 25% metabolizable lysine), and their interaction on performance and carcass composition of feedlot steers during a 170-d feeding period. The basal diet [dry matter (DM) basis] contained 52% dry-rolled corn, 22% dried distillers grains with solubles, 20% corn silage, and 6% vitamin-mineral supplement. Lysine balance was estimated to be −10.3 to −10.8 g for diets that did not contain supplemental lysine, and arginine supply was estimated to be +9.7 g for diets that did not contain supplemental arginine during period 1 (days 0 to 87). Lysine and arginine supplies met or exceeded requirements in period 2 (days 88 to 170). Rumen-protected arginine and lysine were top dressed daily until slaughter at a common BW (622 ± 5.5 kg). Data were analyzed using the MIXED procedure of SAS. Body weight, average daily gain, and DM intake were not affected (P ≥ 0.14) by arginine or lysine supplementation. However, lysine increased gain:feed (P = 0.05) during period 1. Lysine decreased serum urea nitrogen (P = 0.03) on day 87, increased (P = 0.01) longissimus muscle (LM) area, decreased (P ≤ 0.01) fat thickness and yield grade, and tended (P = 0.06) to increase moisture content of LM steaks. There tended to be an interaction for moisture content of steaks (P = 0.09), where arginine supplementation increased moisture content to a greater extent in steaks from cattle supplemented with lysine compared with steaks from cattle not fed supplemental lysine. Arginine tended to increase the proportion of Choice grade carcasses (P = 0.09) but did not change lipid content of steaks (P = 0.59). Arginine tended to decrease serum glutamate (P = 0.09) and lysine (P = 0.07) after 87 d of feeding. In conclusion, supplemental rumen-protected arginine and lysine did not improve performance, but lysine can increase carcass muscle and leanness, and although arginine did not increase lipid content of steaks, it may favorably shift carcasses to a greater quality grade. [ABSTRACT FROM AUTHOR]